Curiosity Rover’s Laboratory Makes First Sample Analysis

http://www.jpl.nasa.gov/news/news.php?release=2012-380

The Curiosity Rover is the first Martian probe to be able to chemically analyze soil samples that it picks up off the ground. The rover did find water molecules in the soil, although nothing remotely organic has yet been found. The experts say that they will continue looking for life around a landmark known as “gale crater”, which is reputed to have a diverse array of different environments.

I am curious as to how we will find evidence for life; if Mars did have organic life early in its history it would have likely been single-celled, anaerobic organisms correct? And these organisms cannot possibly be fossilized like Earth’s Cambrian species. We do not have any Terran evidence of the blue-green algae that once dominated our planet, do we? Perhaps the rover is looking for indirect evidence, such as certain chemical compounds left behind by organic metabolisms. I do not think it will be easy to find evidence of single-celled, soft organisms living in water many millions of years ago; we would need some kind of hard-shelled organism and very unique conditions to find some kind of fossil from what I understand. They must be looking for indirect evidence.